Motor-driven compressor

ABSTRACT

A motor-driven compressor includes a motor driving circuit, which includes a capacitor electrically connected to a circuit board, and a capacitor holder, which holds the capacitor. The capacitor holder includes a side wall body, which covers a side surface of the capacitor, a first retainer, which extends from the side wall body to the circuit board and engages with a first end surface of the capacitor, and a second retainer, which extends from the side wall body in a direction away from the circuit board and holds the second end surface of the capacitor. The length of the second retainer in the extending direction of the second retainer is greater than the length of the first retainer in the extending direction of the first retainer.

BACKGROUND OF THE INVENTION

The present invention relates to a motor-driven compressor that includesa compression unit, which compresses refrigerant, an electric motor,which drives the compression unit, and a motor driving circuit, whichdrives the electric motor.

Japanese Laid-Open Patent Publication No. 2007-263061 describes anexample of such a motor-driven compressor. The motor-driven compressorincludes a motor driving circuit, which includes a planer circuit boardand a plurality of electric components of various types. The electriccomponents, which are electrically connected to the circuit board,include a switching element and a plurality of capacitors, for example.The capacitors are provided on the circuit board. Each capacitor is heldby a capacitor holder.

In such a motor-driven compressor, it is desired to improve resistanceof the capacitors against vibration applied via the capacitor holder sothat the capacitors are restricted from escaping from the capacitorholder.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide amotor-driven compressor that can improve resistance of a capacitoragainst vibration via a capacitor holder.

To achieve the foregoing object, a motor-driven compressor including: acompression unit, an electric motor, a housing, a motor driving circuit,and a capacitor holder is provided. The compression unit is adapted tocompress refrigerant. The electric motor is adapted to drive thecompression unit. The housing accommodates the compression unit and theelectric motor. The motor driving circuit is adapted to drive theelectric motor and includes a circuit board and a capacitor that iselectrically connected to the circuit board. The capacitor holder ismade of a plastic and holds the capacitor. The capacitor holder includesa side wall body, and a first retainer and a second retainer. The sidewall body covers the side surfaces of the capacitor. The first retainerextends from the side wall body toward the circuit board and engageswith a first end surface of the capacitor to hold the capacitor. Thesecond retainer extends from the side wall body in the direction awayfrom the circuit board and engages with a second end surface of thecapacitor to hold the capacitor. The length of the second retainer inthe extending direction of the second retainer is greater than thelength of the first retainer in the extending direction of the firstretainer. The second retainer is elastically deformed so that thecapacitor holder accommodates the capacitor.

Other aspects and advantages of the present invention will becomeapparent from the following description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best beunderstood by reference to the following description of the presentlypreferred embodiments together with the accompanying drawings in which:

FIG. 1 is a partial cross-sectional view showing a motor-drivencompressor according to one embodiment;

FIG. 2 is an exploded perspective view showing a capacitor holder, inwhich film capacitors are held, a coupling base, and a circuit board;

FIG. 3 is a longitudinal cross-sectional view showing the film capacitorand the capacitor holder;

FIG. 4 is a longitudinal cross-sectional view showing the state wherethe film capacitor is inserted into an accommodating chamber; and

FIG. 5 is a perspective view showing film capacitors and a capacitorholder in another embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 4, one embodiment of the present invention willnow be described.

As shown in FIG. 1, a motor-driven compressor 10 includes a housing H.The housing H includes a discharge housing member 11, a suction housingmember 12, and a cover 13, which are made of a metal, preferablyaluminum. The discharge housing member 11, the suction housing member12, and the cover 13 are cylindrical and each include a closed end. Thesuction housing member 12 is coupled to the discharge housing member 11.The suction housing member 12 has a circumferential wall including asuction port (not shown) connected to an external refrigerant circuit(not shown). The discharge housing member 11 includes a discharge port14 connected to the external refrigerant circuit. The suction housingmember 12 accommodates a compression unit 15 (indicated by the brokenlines in FIG. 1), which compresses refrigerant, and an electric motor16, which drives the compression unit 15. Although not shown in thedrawings, the compression unit 15 of the present embodiment includes afixed scroll, which is fixed in the suction housing member 12, and amovable scroll, which faces the fixed scroll.

A stator 17 is fixed to the inner surface of the suction housing member12. The stator 17 includes a stator core 17 a, which is fixed to theinner surface of the suction housing member 12, and coils 17 b, whichare wound around teeth (not shown) of the stator core 17 a. A rotatablerotation shaft 19 extends through the stator 17 in the suction housingmember 12. A rotor 18 is fixed to the rotation shaft 19.

The suction housing member 12 has an end wall 12 a to which the cover 13is coupled. A planer coupling base 31 is arranged between the suctionhousing member 12 and the cover 13. The coupling base 31 is made of ametal, preferably aluminum. The coupling base 31 is coupled to the endwall 12 a of the suction housing member 12. The coupling base 31 isthermally coupled to the suction housing member 12. The coupling base 31serves as a coupling member, which configures a part of the housing H.

The cover 13 and the coupling base 31 define an accommodation chamber 13a in the housing H. The accommodation chamber 13 a accommodates a motordriving circuit 20 that drives the electric motor 16. In the presentembodiment, the compression unit 15, the electric motor 16, and themotor driving circuit 20 are arranged in this order along the axis L ofthe rotation shaft 19 (in the axial direction).

The electric motor 16 is supplied with power that is controlled by themotor driving circuit 20. This rotates the rotor 18 and the rotationshaft 19 at a controlled rotation speed and drives the compression unit15. The driving of the compression unit 15 draws refrigerant from theexternal refrigerant circuit into the suction housing member 12 throughthe suction port, compresses the refrigerant in the suction housingmember 12 with the compression unit 15, and discharges the compressedrefrigerant to the external refrigerant circuit through the dischargeport 14.

The motor driving circuit 20 includes a flat circuit board 21 and aplurality of electric components of various types, which areelectrically connected to the circuit board 21. The circuit board 21 isarranged in the accommodation chamber 13 a such that a mounting surface21 a of the circuit board 21 on which the electric components arearranged is perpendicular to the axis of the rotation shaft 19. Theelectric components include film capacitors 22, for example. The motordriving circuit 20 includes a plurality of film capacitors 22. Each filmcapacitor 22 includes leads 22 a. The leads 22 a electrically connectthe film capacitor 22 to the circuit board 21.

A plastic capacitor holder 23 holds the film capacitors 22. Thecapacitor holder 23, which holds the film capacitors 22, is coupled tothe side of the coupling base 31 that is opposite to the end wall 12 aof the suction housing member 12.

A plurality of bosses 31 f (only one shown in FIG. 1) projects from thesurface of the coupling base 31 that is opposite to the end wall 12 a ofthe suction housing member 12. Bolts B1 are inserted through the cover13 and engaged with the corresponding bosses 31 f to fasten the couplingbase 31 to the cover 13. Accordingly, the cover 13, the coupling base31, and the motor driving circuit 20 are combined to form a module. Abolt B2 fastens the cover 13, which is combined with the coupling base31 and the motor driving circuit 20, to the suction housing member 12.

As shown in FIG. 2, the capacitor holder 23 includes a side wall body 23a, which covers the side surfaces of each film capacitor 22. The sidewall body 23 a includes hollowed polygonal shapes each configured byside walls and face the four sides of the corresponding film capacitor22. The side wall 231 a, which is positioned to face one of the foursides of each film capacitor 22, includes through-holes 23 h, each ofwhich guides a lead 22 a of the corresponding film capacitor 22 to theportion of the circuit board 21 to which the lead 22 a is to be coupled.The side walls 232 a and 233 a face each other and are integrally formedwith the side wall 231 a that includes the through-holes 23 h. Each ofthe side walls 232 a and 233 a includes a first retaining piece 41,which serves as a first retainer, and second retaining pieces 42, whichserves as a second retainer.

The first retaining pieces 41 extend from each side wall body 23 atoward the circuit board 21. The first retaining pieces 41 engage withthe first end surface 221 of the corresponding film capacitor 22 to holdthe film capacitor 22. The second retaining pieces 42 extend from eachside wall body 23 a in a direction away from the circuit board 21. Thesecond retaining pieces 42 engage with the second end surface 222 of thecorresponding film capacitor 22 to hold the film capacitor 22. Thelength L2 of the second retaining pieces 42 in the extending directionof the second retaining pieces 42 is greater than the length L1 of thefirst retaining pieces 41 in the extending direction of the firstretaining pieces 41. The second retaining pieces 42 can be elasticallydeformed.

According to the present embodiment, two first retaining pieces 41 andfour second retaining pieces 42 are provided for each film capacitor 22.Specifically, each of the side walls 232 a and 233 a, which face eachother, includes one of the first retaining pieces 41 and two of thesecond retaining pieces 42. Further, the first retaining piece 41 ispositioned between the two second retaining pieces 42 in each of theside walls 232 a and 233 a. The width H1 of the first retaining pieces41 is greater than the width H2 of the second retaining pieces 42.

As shown in FIG. 3, each first retaining piece 41 protrudes inperpendicularly from the side wall body 23 a of the capacitor holder 23.Each second retaining piece 42 protrudes perpendicularly from the sidewall body 23 a of the capacitor holder 23. The tip end 42 e of thesecond retaining piece 42 is shaped as a hook.

As shown in FIG. 2, the coupling base 31 includes recesses 51, whichserve as engaging portions, in the surface facing the film capacitors22. The recesses 51 are engaged with the corresponding second retainingpieces 42 and limit the amount of the elastic deformation of the secondretaining pieces 42.

The operation of the present embodiment will now be described.

As shown in FIG. 4, when inserting each film capacitor 22 into thecapacitor holder 23, the second retaining pieces 42 are pressed againstthe corresponding film capacitor 22 and elastically deformed. Thisfacilitates the insertion of each film capacitor 22 into the capacitorholder 23.

As each film capacitor 22 is accommodated in the capacitor holder 23,the first retaining pieces 41 engage with the first end surface 221 ofthe corresponding film capacitor 22 to hold the film capacitor 22.Further, as the second retaining pieces 42 return to their originalpositions, the tip ends 42 e of the second retaining pieces 42 engagewith the second end surface 222 of the corresponding film capacitor 22to hold the film capacitor 22. Thereby, each film capacitor 22 is heldby the capacitor holder 23 in the state where the film capacitor 22 isheld between the first retaining pieces 41 and the second retainingpieces 42. This improves the resistance of the film capacitor 22 againstvibration via the capacitor holder 23. Accordingly, even if each filmcapacitor 22 vibrates during the running of the vehicle, the filmcapacitor 22 is restricted from escaping from the capacitor holder 23.

When each film capacitor 22 is inserted through the second retainingpieces 42 into the capacitor holder 23, the leads 22 a are guided by thecorresponding through-holes 23 h to the portions of the circuit board 21to which the leads 22 a are to be connected. This facilitates theconnection operation between the leads 22 a and the circuit board 21.

The advantages of the present embodiment will now be described.

(1) The capacitor holder 23 includes the first retaining pieces 41 andthe second retaining pieces 42. The first retaining pieces 41 extendfrom each side wall body 23 a toward the circuit board 21. The firstretaining pieces 41 engage with the first end surface 221 of thecorresponding film capacitor 22 to hold the film capacitor 22. Thesecond retaining pieces 42 extend from each side wall body 23 a in adirection away from the circuit board 21. The second retaining pieces 42engage with the second end surface 222 of the corresponding filmcapacitor 22 to hold the film capacitor 22. The length L2 of the secondretaining pieces 42 in the extending direction of the second retainingpieces 42 is greater than the length L1 of the first retaining pieces 41in the extending direction of the first retaining pieces 41.

The second retaining pieces 42 are elastically deformed so that thecorresponding film capacitor 22 is accommodated in the capacitor holder23. This facilitates the insertion of the film capacitors 22 into thecapacitor holder 23 when inserting the film capacitors 22 into thecapacitor holder 23 since the second retaining pieces 42 are pressed andelastically deformed by the corresponding film capacitor 22.

As each film capacitor 22 is accommodated in the capacitor holder 23,the first retaining pieces 41 engage with the first end surface 221 ofthe corresponding film capacitor 22 to hold the film capacitor 22.Further, as the second retaining pieces 42 return to their originalpositions, the second retaining pieces 42 engage with the second endsurface 222 of the corresponding film capacitor 22 to hold the filmcapacitor 22. Accordingly, each film capacitor 22 is held by thecapacitor holder 23 in the state where the film capacitor 22 is heldbetween the first retaining pieces 41 and the second retaining pieces42. This improves the resistance of the film capacitor 22 againstvibration via the capacitor holder 23.

(2) A plurality of the second retaining pieces 42 are provided on eachfilm capacitor 22. Each first retaining piece 41 is located betweenadjacent two of the second retaining pieces 42 in each of the side walls232 a and 233 a. The width H1 of the first retaining pieces 41 isgreater than the width H2 of the second retaining pieces 42. Accordingto this, since a plurality of the second retaining pieces is provided oneach film capacitor 22, the holding force for holding the film capacitor22 is improved in comparison to the case where only a single secondretaining piece 42 is provided on each film capacitor 22.

Further, the length L1 of the first retaining pieces 41 in the extendingdirection of the first retaining pieces 41 is less than the length L2 ofthe second retaining pieces 42 in the extending direction of the secondretaining pieces 42, and the width H1 of the first retaining pieces 41is greater than the width H2 of the second retaining pieces 42.Accordingly, the first retaining pieces 41 are less easily elasticallydeformed than the second retaining pieces 42. Thus, when the filmcapacitors 22 are inserted through the second retaining pieces 42 intothe capacitor holder 23, the first retaining pieces 41 are less easilyelastically deformed. Therefore, each film capacitor 22 is restrictedfrom being pushed to the first retaining pieces 41. This allows thefirst end surface 221 of the film capacitor 22 to be reliably engagedwith the first retaining pieces 41.

(3) Each side wall body 23 a of the capacitor holder 23 includes thethrough-holes 23 h, which guide the leads 22 a to the portions of thecircuit board 21 to which the leads 22 a are to be connected. Accordingto this, when inserting the film capacitors 22 through the secondretaining pieces 42 into the capacitor holder 23, the through-holes 23 hguide the leads 22 a to the portions of the circuit board 21 to whichthe leads 22 a are to be connected. This facilitates the connectionoperation between the leads 22 a and the circuit board 21.

(4) The through-holes 23 h are formed in the side wall 231 a of thecapacitor holder 23 positioned to face one of the four sides of eachfilm capacitor 22. The side walls 232 a and 233 a face each other andare integrally formed with the side wall 231 a including thethrough-holes 23 h. Each of the side walls 232 a and 233 a includes thefirst retaining piece 41 and the second retaining pieces 42. Accordingto this, the through-holes 23 h are formed in a side wall different fromthose of which the first retaining pieces 41 and the second retainingpieces 42 are provided. This facilitates the insertion of the filmcapacitors 22 into the capacitor holder 23 in comparison to the casewhere the through-holes 23 h, and the first retaining pieces 41 and thesecond retaining pieces 42 are formed in a single side wall. Since thesingle first retaining piece 41 and the two second retaining pieces 42are provided on the side walls 232 a and 233 a that face each other, theholding force for holding the corresponding film capacitor 22 is furtherimproved.

(5) The recesses 51 are engaged with the corresponding second retainingpieces 42, and limit the amount of the elastic deformation of the secondretaining pieces 42. According to this, the amount of the elasticdeformation of the second retaining pieces 42 is limited by the recesses51 so that the holding force of the capacitor holder 23 for holding thefilm capacitors 22 is further improved.

(6) Since the second retaining pieces 42 are elastically deformed, thesecond retaining pieces 42 include the rigidity less than that of thefirst retaining pieces 41. Therefore, the holding force of the secondretaining pieces 42 for holding the film capacitors 22 is less than theholding force of the first retaining pieces 41 for holding the filmcapacitors 22. Accordingly, in the present embodiment, the four secondretaining pieces 42 are provided for each film capacitor 22. Thisincreases the number of the portions in the second end surface 222 ofthe film capacitor 22 by which the film capacitor 22 is held.Accordingly, the holding force for holding the film capacitor 22 isensured.

The above described embodiment may be modified as follows.

As shown in FIG. 5, two first retaining pieces 41 may be provided oneach of the side walls 232 a and 233 a, which face each other. Thenumber of the first retaining pieces 41 and the second retaining pieces42 is not limited.

In the embodiment, it is not necessary to provide the first retainingpieces 41 and the second retaining pieces 42 on each of the side walls232 a and 233 a, which face each other. For example, the first retainingpieces 41 and the second retaining pieces 42 may be formed on the sidewall 231 a, which includes the through-holes 23 h. For example, thefirst retaining pieces 41 or the second retaining pieces 42 may beformed on the side wall 231 a, which includes the through-holes 23 h.

In the embodiment, for example, the coupling base 31 may includeprotrusions such that the protrusions engage with the second retainingpieces 42 to limit the amount of the elastic deformation of the secondretaining pieces 42. In this case, the protrusions serve as engagingportions.

In the embodiment, the width H1 of the first retaining pieces 41 may bethe same as the width H2 of the second retaining pieces 42. The width H1of the first retaining pieces 41 may be less than the width H2 of thesecond retaining pieces 42.

In the embodiment, the coupling base 31 may be omitted. Further, thecapacitor holder 23 may be coupled to the end wall 12 a of the suctionhousing member 12. In this case, the end wall 12 a of the suctionhousing member 12 serves as a coupling member to which the capacitorholder 23 is coupled. The recesses 51 may be formed in the surface ofthe end wall 12 a facing the capacitor holder 23.

In the embodiment, the number of the film capacitor 22 is notparticularly limited. That is, the number may be appropriately changed.

In the embodiment, the capacitors may include an electrolytic capacitor,for example.

In the embodiment, the motor driving circuit 20 may be located radiallyoutward of the rotation shaft 19, for example.

In the embodiment, the compression unit 15 may be of a piston type or avane type, for example.

In the embodiment, the motor-driven compressor 10 may be used for anyair conditioning device other than that installed in a vehicle.

Therefore, the present examples and embodiments are to be considered asillustrative and not restrictive and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalence of the appended claims.

1. A motor-driven compressor, comprising: a compression unit adapted tocompress refrigerant; an electric motor adapted to drive the compressionunit; a housing that accommodates the compression unit and the electricmotor; a motor driving circuit that is adapted to drive the electricmotor and includes a circuit board and a capacitor that is electricallyconnected to the circuit board; and a capacitor holder that is made of aplastic and holds the capacitor, wherein the capacitor holder includes aside wall body, which covers a side surface of the capacitor, a firstretainer, which extends from the side wall body toward the circuit boardand engages with a first end surface of the capacitor to hold thecapacitor, and a second retainer, which extends from the side wall bodyin a direction away from the circuit board and engages with a second endsurface of the capacitor to hold the capacitor, wherein a length of thesecond retainer in an extending direction of the second retainer isgreater than a length of the first retainer in an extending direction ofthe first retainer, and the second retainer is elastically deformed sothat the capacitor holder accommodates the capacitor.
 2. Themotor-driven compressor according to claim 1, wherein the secondretainer is one of a plurality of second retainer provided for thecapacitor, the first retainer is provided such that the first retaineris located between an adjacent pair of the second retainers, and a widthof the first retainer is greater than a width of each of the secondretainer.
 3. The motor-driven compressor according to claim 1, whereinthe capacitor includes a lead, which protrudes from the capacitor,wherein the capacitor is electrically connected through the lead to thecircuit board, and the side wall body includes a through-hole, whichguides the lead to a portion of the circuit board to which the lead isto be connected.
 4. The motor-driven compressor according to claim 3,wherein the capacitor has a substantially cuboid shape, the side wallbody has a hollowed polygonal shape configured by a plurality of sidewalls, which surround four sides of the capacitor, the through-hole isformed in one of the side walls that is positioned to face one of thefour sides of the capacitor, and the first retainer and the secondretainer are provided in each of two of the side walls that face eachother, wherein the two side walls that face each other are formed to becontinuous with the side wall in which the through-hole is formed. 5.The motor-driven compressor according to claim 1, further comprising acoupling member, which configures a part of the housing, wherein thecapacitor holder is coupled to the coupling member, and the couplingmember includes an engaging portion, which engages with the secondretainer to limit an amount of elastic deformation of the secondretainer.
 6. The motor-driven compressor according to claim 5, whereinthe engaging portion includes a recess.
 7. The motor-driven compressoraccording to claim 1, wherein the capacitor is a film capacitor.
 8. Themotor-driven compressor according to claim 1, further comprising arotation shaft that is accommodated in the housing and rotatedintegrally with a rotor of the electric motor, wherein the compressionunit, the electric motor, and the motor driving circuit are arranged inthis order along an axis of the rotation shaft.
 9. The motor-drivencompressor according to claim 1, wherein the motor-driven compressor ismounted on a vehicle.